The present invention relates to a method and device for the customization of a helmet with a night vision optical device.
Helmets for pilots of military aircraft that have to carry out night missions are fitted out with night vision devices provided with electronic light intensifiers. The earliest night vision devices fixed to these helmets were relatively bulky &lt;&lt;binocular&gt;&gt; type devices. They gave way to more compact &lt;&lt;eyeglass&gt;&gt; type devices with folded optical paths.
These night vision devices have to be adapted to the vision of each user, and their settings are limited and relatively complicated to make, especially as the size of their pupil is relatively small (generally with a diameter of 10 to 15 mm). This makes it necessary to achieve the precise positioning of their eyepieces in relation to the pilot's eyes.
Now, these night vision devices are linked to the helmet, and there is very little precision in the position of the helmet with respect to the pilot's head, even when the helmet is provided with elements for easy wear and customization (generally consisting of the injection of foam between the inner shell and the user's head). Furthermore, the very geometry of the helmet is such that it is not possible to obtain a very precise positioning of the inner shell with respect to the fastening base of the night vision device, which is fixed to the outer shell.
To resolve these problems of relative positioning, firstly between the pilot's head and the inner shell and, secondly, between the inner shell and the outer shell, it could be planned to add different adjusting devices for adjustment according to the different degrees of freedom (inter-pupil distance and geometrical orientation with major lengths of travel to compensate for the different positioning errors and manufacturing tolerance values). Such approaches have two major drawbacks. The first drawback is the substantial mass of these setting devices. The second drawback, in the case of the use of night vision eyeglasses, is the fact that disparities in position between the optical module of these eyepieces and the helmet have repercussions on the relative position between these eyepieces and the visor: this visor, which is linked to the helmet, should be capable of passing in front of these eyepieces without catching them. The result thereof is that these approaches result in an increased complexity of the hinging mechanism of the visor and/or greater bulk in the visor and/or greater bulk in the helmet.